An interesting article which ultimately concludes that it’s “safe enough.” However, right there in the article is something which contradicts its conclusion:

As far as your Safari bookmarks or iPhone photos, however, that information is only given out when required by law, such as when it’s required by court order. “We may also disclose information about you if we determine that, for purposes of national security, law enforcement, or other issues of public importance, disclosure is necessary or appropriate,” Apple wrote in its privacy policy.

In other words, it’s not really safe at all. If it were, it would be impossible for Apple to ever disclose anything, for any reason, because they wouldn’t be able to get to it to disclose it.